The former couple, who have a son together, Henry Chance, are seeking joint custody of their four-year-old.

A joint statement issued on behalf of the Hollywood actress and her ex-partner, who were engaged but did not marry, said that they had split up some time ago and did not give a reason for the break-up.

It said: "Rachel Weisz and Darren Aronofsky have been separated for some months. They remain close friends and are committed to raising their son together in New York City."

British actress Rachel's credits include The Mummy, The Lovely Bones and My Blueberry Nights. She won a best supporting actress Oscar for The Constant Gardner in 2006.

Earlier this year she worked on upcoming film The Dream House with James Bond star Daniel Craig.

US director Darren, 41, enjoyed acclaim with The Wrestler, starring Mickey Rourke, and his next film, Black Swan, starring Natalie Portman, has been tipped for Oscar glory. His other credits include Requiem For A Dream and Pi.

Cambridge graduate Rachel, who was born in London, the daughter of Hungarian parents who fled Nazi Germany to settle in Hampstead, has previously dated Neil Morrissey and Sam Mendes.

Darren proposed to Rachel in New York's Times Square after they finished the 2006 movie The Fountain, their only film together, but they have never married.

She has said of Darren: "Seeing his films, you'd think he's this weird, dark, intense guy, but I don't live with a dark person. He's really good at life, very good at going to the park and having a good time. What he is is organised. He doesn't live in disorder or chaos."